Facilities such as the article transport facility described above are configured to cause article transport vehicles to travel based on travel commands from a ground side travel controller to transport articles among article transfer locations with the article transport vehicles.
And an example of such article transport facility is disclosed in JP Publication of Application No. 2006-259877 (Patent Document 1).
In Patent Document 1, an obstacle sensor for detecting the position of an article is provided to each article transport vehicle.
And a vehicle side travel controller is configured to change the target travel speed to a reduced travel speed which is less than the normal travel speed when an article exists within a set distance from the article transport vehicle, based on detected information for the obstacle sensor.
Incidentally, in the conventional article transport facility described above, articles may be placed directly on the floor at a side of the travel path.
The positions of such articles are stored in advance in the vehicle side travel controller so that they would not be determined to be interfering objects or obstacles.
However, in the article transport facility disclosed in the Patent Document 1 described above, the obstacle sensor provided to the article transport vehicle detects the position of any interfering objects.
Thus, for example, if there is an article, such as an article that is directly placed on the floor, between an article transport vehicle and an interfering object, and if that article is not a target of detection and thus is not determined to be an interfering object, then because the interfering object can be hidden by this article that is not a target of detection, the obstacle sensor would not be able to detect the interfering object.
And if the interfering object is a movable object such as a human worker, etc., the interfering object may move and appear suddenly in front of the article transport vehicle.
And when this happens, the interfering object can be detected by the obstacle sensor only after the interfering object appears in front of the article a transport vehicle.
Thus, the article transport vehicle would be traveling at a normal travel speed when the interfering object sensor detects an interfering object; thus, there is a possibility that the article transport vehicle may interfere, or collide, with the interfering object before the vehicle is able to slow down and stop.